Selective Plastic Photo Upcycling to Acetic Acid via Coupled Oxidation and CO Reduction Over an S-Scheme g-CN/FeO Heterojunction.

Photo-assisted upcycling of nonbiodegradable plastic waste offers a sustainable route to mitigate plastic pollution, yet remains limited by low efficiency and poor product selectivity. Herein, we report a S-scheme heterojunction photocatalyst composed of sulfur-doped and sulfonic-acid functionalized graphitic carbon nitride coupled with iron oxide (S-g-CN/FeO) for selective plastic upcycling under ambient conditions. The synthesized catalyst converts polyethylene, polystyrene, and polyethylene terephthalate into acetic acid under simulated sunlight, achieving up to 77% polyethylene conversion with a yield rate of 0.42 mmol g⋅cat h. Radical trapping experiments identify electrons and holes as the key reactive species. Combined Fourier transform infrared spectroscopy (FTIR), UV-Visible (UV-Vis) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and as chromatography analyses confirm CO formation by photooxidation of polyethylene followed and subsequent reduction to acetate. Importantly, the photo upcycling of the commercial plastic products further validated the practicality of this approach for sustainable C chemicals production.